Techniques are available to the pulp and paper industry to determine the shive content in a pulp. Each focuses on shives of a particular size. One of the techniques as disclosed in U.S. Pat. No. 4,342,618 invented by Karnis et al, involves the use of screens. Another technique as disclosed in U.S. Pat. No. 4,399,691 invented by Janssen and assigned to the present assignee, involves the use of a gap.
In each technique, the size of the retained or trapped fibres is slightly larger than the mesh or the gap. The resulting fibre content calculation, therefore, is based on a given size of fibres, that are slightly larger than the size of the mesh or the gap. In many cases however, a series of fibre content calculations over a particular range of fibre sizes would yield more important information as to the condition of the prepared pulp. With present techniques, such a series would require the use of a number of different sized meshes or gaps, resulting in a long and expensive procedure.
In addition, a continuous monitoring of a range in fibre sizes, or a fibre size distribution, would greatly improve the analysis of wood pulp. This is especially so in the paper making processes that practise a continuous treatment of the wood pulp. Present techniques however, are insufficient in a continuous monitoring mode due to high labour requirements and overly long cycle time periods. Furthermore, characteristics of the pulp fibre must be assumed constant on these long cycle time periods, and therefore leading to further inaccuracies.